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import numpy as np
import pytest
import pandas.util._test_decorators as td
import pandas as pd
import pandas._testing as tm
from pandas.core.internals.blocks import NumpyBlock
class BaseCastingTests:
"""Casting to and from ExtensionDtypes"""
def test_astype_object_series(self, all_data):
ser = pd.Series(all_data, name="A")
result = ser.astype(object)
assert result.dtype == np.dtype(object)
if hasattr(result._mgr, "blocks"):
blk = result._mgr.blocks[0]
assert isinstance(blk, NumpyBlock)
assert blk.is_object
assert isinstance(result._mgr.array, np.ndarray)
assert result._mgr.array.dtype == np.dtype(object)
def test_astype_object_frame(self, all_data):
df = pd.DataFrame({"A": all_data})
result = df.astype(object)
if hasattr(result._mgr, "blocks"):
blk = result._mgr.blocks[0]
assert isinstance(blk, NumpyBlock), type(blk)
assert blk.is_object
assert isinstance(result._mgr.arrays[0], np.ndarray)
assert result._mgr.arrays[0].dtype == np.dtype(object)
# check that we can compare the dtypes
comp = result.dtypes == df.dtypes
assert not comp.any()
def test_tolist(self, data):
result = pd.Series(data).tolist()
expected = list(data)
assert result == expected
def test_astype_str(self, data):
result = pd.Series(data[:5]).astype(str)
expected = pd.Series([str(x) for x in data[:5]], dtype=str)
tm.assert_series_equal(result, expected)
@pytest.mark.parametrize(
"nullable_string_dtype",
[
"string[python]",
pytest.param("string[pyarrow]", marks=td.skip_if_no("pyarrow")),
],
)
def test_astype_string(self, data, nullable_string_dtype):
# GH-33465, GH#45326 as of 2.0 we decode bytes instead of calling str(obj)
result = pd.Series(data[:5]).astype(nullable_string_dtype)
expected = pd.Series(
[str(x) if not isinstance(x, bytes) else x.decode() for x in data[:5]],
dtype=nullable_string_dtype,
)
tm.assert_series_equal(result, expected)
def test_to_numpy(self, data):
expected = np.asarray(data)
result = data.to_numpy()
tm.assert_equal(result, expected)
result = pd.Series(data).to_numpy()
tm.assert_equal(result, expected)
def test_astype_empty_dataframe(self, dtype):
# https://github.com/pandas-dev/pandas/issues/33113
df = pd.DataFrame()
result = df.astype(dtype)
tm.assert_frame_equal(result, df)
@pytest.mark.parametrize("copy", [True, False])
def test_astype_own_type(self, data, copy):
# ensure that astype returns the original object for equal dtype and copy=False
# https://github.com/pandas-dev/pandas/issues/28488
result = data.astype(data.dtype, copy=copy)
assert (result is data) is (not copy)
tm.assert_extension_array_equal(result, data)
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